Touch based user-interface systems are becoming more ubiquitous, for example mobile phones, tablets, ebook readers, GPS navigation systems, still and video cameras etc.
There are many different touch-screen technologies available, these provide sophisticated control over the device's operation, but require the user to touch the “touch screen”. Although this is intuitive and provides for precise input (e.g. selecting one from 20 icons or widgets on a screen) there is a disadvantage, they require the user to touch the screen.
This leaves marks on the screen and under certain conditions more than other. For example, using an ebook reader to read a recipe in a kitchen when cooking (with hands covered in flour or dough), reading through a technical manual for a bicycle when there is grease on hands or in a sterile environment such as an operating theater to avoid contamination.
One problem with known non-contact gesture interfaces, is that they require a sensor module comprising plurality of photodetectors to detect the movement, but for various reasons (aesthetics, compactness etc.) the sensor should take up as small an area as possible. This results in each photodetector only receiving a small amount of light, particularly when the light level incident on the sensor is low.
It would be desirable to have a non-contact gesture interface while addressing the problem of low light levels over several detectors.